Air quality readings were within the normal range, and an air quality warning has not been issued, officials said.

Although a warning hadn't been issued, video and photographs showed ash raining down around the surrounding on homes, vehicles, plants and roadways.

Schools in the area were initially told to shelter in place, but the order was no longer in place at every campus, according to Tammy Khan with the Torrance Unified School District. A list of schools where the warning was in place was not immediately available.

Police had also earlier stated no shelter in place orders had been issued, but a late-morning alert sent out to residents advised young children and people with certain medical conditions to stay indoors.

Those in the area were also being told not to use their air conditioning.

The refinery covers roughly 750 acres, according to Exxon Mobil Corporation. It processes an average of 155,000 barrels of crude oil per day and produces 1.8 million gallons of gasoline each year.